Chick AnxietyDepression Screening Model

The chick anxiety–depression model is a hybrid, dual pharmacological screening assay in which both anxiety and depression present sequentially over a 2 h isolation period. This separation stress paradigm utilizes socially raised domestic fowl chicks, aged 4–6 days posthatch, that are isolated from conspecifics during which distress vocalizations (DVocs) are recorded. DVoc rates during the first 5 min are high and represent the anxiety-like phase; DVoc rates decline over the next 20–30 min to about 50% the initial rate and then stabilize for the remainder of the test session. This last 90 min represents the depression-like phase. These two phases are pharmacologically dissociable in that anxiolytics reduce the rate of DVocs during the anxiety-like phase and antidepressants delay the onset of the depression-like phase by attenuating the decline of DVoc rates.